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), micellar liquid chromatography has limited measurable ranges (Kulikov, 2007), HPLC-ICP- MS and HPLC-UV-HG-AFS depend on complex instruments, and GC-MS depends on complex derivatization reactions, more than that, isobaric interference of 40Ar2 with the most widespread isotope 80Se (49.6%) is serious in MS analysis (Tie et al., 2007). Here, we will introduce a simple method to determine the selenium content based on RP-HPLC. Golden needle mushroom (Flammulina velu- tipes) is a good source of carbohydrates, proteins, fi bers, essential amino acids and minerals

Abstract

In the present paper we describe results on the synthesis and lipophilicity determination of a series of biologically active compounds based on their heterocyclic structure. For synthesis of styrylquinoline-based compounds we applied microwave irradiation and solid phase techniques. The correlation between RP-HPLC retention parameter log k (the logarithm of retention factor k) and log P data calculated in various ways is discussed, as well as, the relationships between the lipophilicity and the chemical structure of the studied compounds.

Validated RP-HPLC and TLC methods for simultaneous estimation of tamsulosin hydrochloride and finasteride in combined dosage forms

Reversed-phase high-performance liquid chromatography (RP-HPLC) and thin-layer chromatography (TLC) methods have been developed and validated for simultaneous estimation of tamsulosin hydrochloride and finasteride in bulk drug and in combined dosage forms. RP-HPLC separation was achieved on a Phenomenex C18 column using methanol/0.02 mol L-1 ammonium acetate buffer/triethylamine (79.9 + 20 + 0.1, V/V/V) (pH 9.2) as mobile phase. TLC separation was achieved on an aluminium-backed layer of silica gel 60 F254 using toluene/methanol/triethylamine (9 + 1.5 + 1, V/V/V) as eluent. Quantification was achieved with photodiode array (PDA) detection at 235 nm over the concentration range 0.5-16 and 1-50 μg mL-1 with mean recovery of 99.8 ± 0.9 and 100.0 ± 0.8% for tamsulosin hydrochloride and finasteride, respectively, by the RP-HPLC method. Quantification was achieved with UV detection at 270 nm over the concentration range 100-2000 ng per spot and 250-5000 ng per spot with mean recovery of 98.9 ± 0.9 and 99.6 ± 0.7 % for tamsulosin hydrochloride and finasteride, respectively, by the TLC method. Both methods are simple, precise, accurate and sensitive and are applicable to the simultaneous determination of tamsulosin hydrochloride and finasteride in bulk drug and in combined dosage forms.

Use of chemometrics for development and validation of an RP-HPLC method for simultaneous determination of haloperidol and related compounds

A rapid resolution reversed-phase high performance liquid chromatographic (RR RP-HPLC) method has been developed and validated for simultaneous determination of haloperidol and six related compounds. Investigated matrix was a laboratory mixture of a therapeutic active substance haloperidol and its six related compounds in concentration ratio 300:1. Experimental design was used during method optimization (full factorial 23 design) and robustness testing (Central Composite Circumscribed design). Three factors: organic phase variation during gradient elution, flow rate and gradient rise time were independent variables. To estimate the system response during the optimization procedure and robustness testing, resolution (Rs) and a chromatographic response function (CRF) were used. Chromatography was performed with the mobile phase containing phosphate buffer pH 6.5 and acetonitrile as organic modifier. Separation was achieved using gradient elution (organic phase fraction changed linearly from 20 to 72 %) over 7 min. A Zorbax Eclipse XDB C18 Rapid Resolution HT 4.6 mm x 50 mm, 1.8 μm particle size, column was used at 25 °C at a flow rate of 1.5 mL min-1. UV detection was performed at 230 nm. The total time for chromatographic separation was 5.5 min with a total analysis time of 7.0 min. The method was validated for its linearity, precision, modal recovery and robustness.

Simple RP-HPLC method for determination of triple drug combination of valsartan, amlodipine and hydrochlorothiazide in human plasma

A simple RP-HPLC method for the quantification of valsartan (VAL), amlodipine (AML) and hydrochlorothiazide (HCT) in human plasma was developed and validated. VAL, AML and HCT were resolved using a Gemini C18 column and mobile phase gradient starting from 20 % acetonitrile and 80 % 10 mmol L-1 ammonium formate (V/V, pH 3.5 ± 0.2, by formic acid) to 70 % acetonitrile and 30 % 10 mmol L-1 ammonium formate, over 20 minutes, with a flow rate of 1 mL min-1. The samples were purified by protein precipitation and extraction. Telmisartan was used as internal standard. The method was validated according to USFDA and EMEA guidelines with good reproducibility and linear responses R = 0.9985 (VAL), 0.9964 (AML), and 0.9971 (HCT). RSDs of intra- and inter-day precision ranged 2.2-8.1 and 4.6-11.7 %, respectively, for all three drugs. Mean extraction recoveries of three QCs for the triple drug combination were 76.5 (VAL), 72.0 (AML) and 73.0 (HCT) % for human plasma. Although the LC-MS/MS method is more sensitive than HPLC, HPLC is still suitable for preliminary pharmacokinetic study. The experiments performed demostrated that simultaneous determination of all components of the triple drug combination in human plasma can be done by this method. Proposed method can be also used for guidance to the LC-MS/MS method.

.28 639.65 2 (3.78, 4.63) 85.70 30% H 2 O 2 416,403±538.13 0.12 310.69 1 (3.47) 94.25 Thermal 368,652.7±578.77 0.15 334.15 1 (3.47) 83.60 From the evaluation of peak areas of stored drug solution [when stored for 72 h in the optimized mobile phase at room temperature (25±1°C) and under freezing conditions (4±0.5°C)] and peak areas obtained from a freshly prepared solution of ROC, it was inferred that ≥99% of the ROC remained unchanged. 3.4 Relevance of developed RP-HPLC method for the evaluation of rosuvastatin in developed SNEDDS On verifying the validity of the newly

Abstract

Two reversed-phase high performance liquid chromatography analytical methods (Method I and Method II) for determination of assay of recombinant human thrombin in pharmaceutical formulations were developed and validated. Analysis was performed on chromatographic system Agilent 1200 series SL with diode array detection and mass selective detection.

Method I was intended for faster determination of thrombin assay. Gradient programme was optimised to achieve sufficient separation and acceptable runtime. Chromatographic analysis was performed on analytical column Grace Vydac, C4 250 × 4.6 mm, 5 mm. Method II is Method I adapted to use the mass selective detector. Chromatographic separation was performed on analytical column Zorbax 300SB-C8 SolvSaver Plus, 150 × 3 mm, 3.5 mm. Both analytical methods were validated with respect to specificity, linearity, precision and accuracy. The response of thrombin was a linear function of concentration over the range 0.1-1.0 mg/ml. Precision and accuracy of thrombin was evaluated at three concentration levels low (0.2 mg/ml), medium (0.4 mg/ml) and high (0.8 mg/ml).

Both validated methods have been successfully applied for determination of assay and thrombin degradation products in pharmaceutical formulations.

. 77 (2015) 14–23; https://doi.org/10.4103/0250-474X.151577 13. P. Shende and R. Gaud, Validated RP-HPLC analysis of irinotecan HCl in the bulk material and in pharmaceutical formulations, Acta Chromatogr. 21 (2009) 71–82; https://doi.org/10.1556/AChrom.21.2009.1.6 14. T. Xuan, J. A. Zhang and I. Ahmad, HPLC method for determination of SN-38 content and SN-38 entrapment efficiency in a novel liposome-based formulation, LE-SN38, J. Pharm. Biomed. Anal. 41 (2006) 582–588; https://doi.org/10.1016/j.jpba.2005.10.051 15. L. Kumar, M. S. Reddy, R. S. Managuli and K

Pharmacy, Ernst-Moritz-Arndt University, D-17487 Greifswald, Germany *Corresponding author A sensitive and specific RP-HPLC assay was devel- oped to measure the levels of polymorphonuclear elastase (PMN-E) activity in growing cell cultures. By combining a pre-incubation of the cells with a rela- tively non-toxic, PMN-E-specific inhibitor, MeOSuc- Ala-Ala-Pro-Val-chloromethylketone (MAAPVCK), the p-nitroaniline formed by the hydrolysis of the sub- strate MeOSuc-Ala-Ala-Pro-Val-p-NA by PMN-E is quantified. Elastase-like activity was measured in 14 human cells lines: 13

Abstract

A simple RP HPLC method for quantification of betamethasone dipropionate (BDP) in gingival crevicular fluid (GCF) has been developed and validated. GCF represents a valuable matrix for therapeutic monitoring of drugs used in the treatment of periodontal disease. The proposed method involves single step extraction for sample preparation. The calibration curve for BDP was linear over the concentration range of 0.10-2.00 μg mL-1 (R2 = 0.9971). RSD values of intra- and inter-day precision ranged 2.2-4.5 and 1.6-5.7 %, while accuracy values were higher than 96.6 and 97.0 %, respectively. The described method can be successfully applied for determination of betamethasone concentrations in GCF obtained from patients with chronic periodontitis after local treatment with BDP cream 0.5 mg g-1.